Southern Water is set to increase customers' bills by 91 per cent over the next few years, it has been revealed.

The water firm, which covers the Isle of Wight, will by 2030 be charging households £915 a year, the Consumer Council for Water has said.

It comes as the beleaguered company faces repeated criticism over storm overflows from waste treatment centres.

CCW chief executive Mike Keil said the hike in bills across the country would be 'a massive surprise to people'.

He said: "People do want to see improvements, they do understand that takes investment, but I think the scale of what’s being proposed here is going to come as a real shock and this is why water companies have doubled down on their efforts to explain what people are getting for their money."

Nearby Portsmouth Water is set to hike bills by 31 per cent to £157 by 2030.

Average Southern Water bills in 2014 were around £436 and are this year around £420. The company's proposed hike over the next six years is the largest in the country.

Southern Water said it offers 156,000 households a discount of 45 per cent minimum.

Chief customer officer Katy Taylor said: “We share everyone’s concerns about rising payments in the face of a cost-of-living crisis.

"That's why we continue to support customers who need help to pay their bills, offering 156,000 households a minimum 45 per cent discount.

"The water needs of our water-stressed region pose a unique set of challenges which require significant investment, to reduce the use of storm overflows, safeguard water supplies for a rapidly growing population, and protect the environment.

“We have put forward billing options to Ofwat and these will be decided by the regulator in due course.”

The company previously said it was spending around £1,500 per household on improving its network.

This is part of a £3bn spend between 2020 and 2025 to improve performance.

The Turnaround Plan was designed to reduce flooding and pollution incidents.